Intra S-GW Handover with Collapsed UPF
The following illustration describes the intra-SGW handover call flow with collapsed UPF.

Step | Description |
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1 |
As part of UE initial attach, N4 and Sxa session is already established with SMF and UPF. At UPF, N4+Sxa session exists and are interconnected. The MME sends Modify Bearer Request to the SGW-C/cnSGW. The SGW-C/cnSGW updates eNodeB F-TEID in FAR. |
2 |
The SGW-C/cnSGW sends Sx Modify Request (Sxa) to the UPF. The UPF:
|
3 | The UPF sends Sx Modify Response (Sxa) to the SGW-C/cnSGW. |
4 | The SGW-C/cnSGW sends Modify Bearer Response to the MME. |